Batting against former batterymates

If any of you are fans of ESPN’s Baseball Today podcast, or the work of ESPN research samurai Mark Simon, you might be familiar with the “ridiculous question of the day” feature on the podcast. And if you listened closely last Friday, you might have noticed that the answer to a previous “ridiculous question” (the one about what players have played in the opening games at the most stadiums) was submitted by some guy who writes a website called Oh hey, that’s me. So imagine my surprise when my reward for helping out turned out to be not an ESPN tote bag or an Eric Karabell bobblehead, but homework. Some other listener sent in a question about whether catchers hit better against pitchers that they’ve caught for, on the theory that they’d be especially familiar with what the pitcher likes to throw, and that would give them an advantage. I have to say that my policy toward homework has long been that if you start doing it, teachers will only want you to do more… but this sounded interesting, and I do consider myself a Mark Simon fan… and, it turns out this is another of those things that I can get at with the data I already have lying around (all from, as usual). And I probably would have done this anyway because I’m oddly fascinated by the Ridiculous Question of the Day.

So, I looked at plate appearance in the 2010 and 2011 season, and isolated those where the batter had caught for the pitcher sometime between 2005 and the time of that plate appearance. Then collecting the 89 batters that fit that criteria, I compared their combined batting stats facing former batterymates against their combined batting stats in 2010 and 2011 against pitchers that they never caught for. As it turns out, this data shows that their may be a small advantage for a catcher when he’s facing a former batterymate.

Against Former Battery Mates Against other pitchers
OPS .741 .714
avg .257 .250
SLG .421 .393
OBP .320 .321
PA per HR 31.3 38.9
PA per HBP 121.2 107
Plate Appearances 1,818 40,784

As you can see, the OPS of this group of catchers is 3.8% higher against former batterymates than against all other pitchers, and that OPS increase is coming entirely from the Slugging part of the equation. OBP is nearly dead even. Also, catchers in 2010 and 2011 hit 24.2% more home runs per plate appearance when facing pitchers they used to catch for, but they get hit by pitches about 12% less often. (Whether you consider that an advantage or a disadvantage is up to you, but I consider getting hit by less pitches a bad thing.)

Below are the results for the group of catchers who had at least 50 plate appearances in the last two seasons, facing pitchers they used to catch for.  Mike Napoli leads the group in plate appearances, HBPs, and homers with 124 plate appearances, 3 plunks and 9 homers against pitchers he used to catch for.

vs former battery mates vs other pitchers
Mike Napoli 124 .952 3 .895 11 .057
Victor Martinez 121 .911 0 .840 2 .072
Yorvit Torrealba 82 .778 0 .705 3 .073
Miguel Olivo 73 .836 0 .685 2 .150
Ronny Paulino 70 .653 0 .666 1 -.013
Jose Molina 66 .531 0 .761 6 -.230
Matt Treanor 65 .440 0 .636 9 -.196
Carlos Ruiz 53 .867 1 .794 15 .073
Kelly Shoppach 52 .641 1 .623 14 .018

While I’m on the subject, I might as well figure out which catchers have been plunked the most times by former batterymates. That’ll be coming soon. The short answer is, probably Jason Kendall.

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